Posted
by
kdawson
on Friday December 11, 2009 @11:02AM
from the magnetoelectric-quantum-wheel dept.

KentuckyFC writes "According to quantum mechanics, a vacuum will be filled with electromagnetic waves leaping in and out of existence. It turns out that these waves can have various measurable effects, such as the Casimir-Polder force, which was first measured accurately in 1997. Just how to exploit this force is still not clear. Now, however, a researcher at an Israeli government lab suggests how it could be possible to generate propulsion using the quantum vacuum. The basic idea is that pushing on the electromagnetic fields in the vacuum should generate an equal and opposite force. The suggestion is that this can be done using nanoparticles that interact with the vacuum's electric and magnetic fields, generating the well-known Lorentz force. In most cases, the sum of Lorentz forces adds up to zero. But today's breakthrough is the discovery of various ways to break this symmetry and so use the quantum vacuum to generate a force. The simplest of these is simply to rotate the particles. So the blueprint for a quantum propulsion machine described in the paper is an array of addressable nanoparticles that can be rotated in the required way. Although such a machine will need a source of energy, it generates propulsion without any change in mass. As the research puts it with magesterial understatement, this might have practical implications."

That could only work if the vacuum had a velocity in relation to the craft - a preferred reference frame of its own. The whole point of relativity is that there is no such priviliged reference frame.

Without that, there's nothing to define how much you have accelerated, nothing the crafts own frame can relate to, so constant power into such a system ought to create constant force. With a fixed mass, that means that you're putting kinetic energy into the system linearly with respect to speed, but gaining kin

It is not. The spacecraft is rotated one way, and as a reaction the gyro is rotated the other way.

If you have to put something into a system (like, say, electricity) to get something out (like, say, motive force), then that's not against the laws of physics, or even remotely technically difficult.

It doesn't matter how much you put into a system, you still have to balance momentum, or you're breaking very fundamental laws. You can not create momentum in one direction without also creating an equal momentum in the opposite direction.

It turns out that there is no such thing as a classical vacuum. Instead, you have a state where particle/antiparticle pairs are spontaneously created and destroyed with typically net zero force. So, the definition of vacuum has been reformed.

That's not at all connected. What you are thining of is as velocity of an object increases its mass will increase (this is actually a little more complicated. This is only true for things with positive rest mass. If you have zero rest mass for example then this doesn't happen, but you will always be traveling at the speed of light anyways. If you are a tachyon and hus have imaginary rest mass and move faster than the speed of light in a vacuum then what happens as you change velocity is more complicated). This will still happen. The key to this sort of drive is that you don't *lose* mass as part of your reaction. Rockets, ion engines, and pretty much every other method of moving things requires you to push against something else to move. A rocket works by sending out particles from one end and so conservation of mass forces it in the other direction. An ion engine works the same way but instead of using hot fast particles uses little ions accelerated by a magnetic field.

The key to this sort of engine is that it doesn't do that, It can accelerate without throwing off mass. But the object will still gain mass as it accelerates nearer to the speed of light. In practice, the second part really won't matter for any practical engine since we will be moving so much slower than the speed of light. The key idea at some level is that you don't need to lose fuel to accelerate (you just lose energy).

Well technically the car is losing a slight bit of mass because of the energy change, but that's not relevant to the propulsion, a car isn't a rocket. The car is pushing against the earth and transferring that momentum to the earth.

electric cars are based on magnetic coils producing a kinetic force. Put an electric car in a zero G vacuum and you won't go anywhere. The difference is that a quantum propulsion engine does not rely on a tangible surface to push against.

Thanks for the thorough information. How does this throwing off mass thing relate to electric cars? Do electric cars accelerate without loosing mass?

It's not about losing mass necessarily, it's about Newton's 3rd Law / Conservation of Momentum. For something to accelerate forward, something else (the surface of the earth) must accelerate in the opposite direction such that momentum is conserved.

The concept of Conservation of Momentum and rocket propulsion is often explained using the analogy of a boat on the lake with a bunch of rocks in it. If you throw rocks off the back of the boat, conservation of momentum means your boat will be propelled forward. Now, that's a pretty silly way to propel a boat when you can just use a paddle or propeller to push the water backwards and your boat forward.

Rockets in space don't have that luxury. So they pretty much have to carry a bunch of "reaction mass" with them and throw it at high speed out the ass end of the rocket.

This invention, if it pans out, would be more like a propeller for spacecraft, pushed by and pushing against the short-lived particles that spring in and out of existence in vacuum. I have to imagine that the amount of thrust would be miniscule, but not having to carry reaction mass would be a huge advantage.

Until we find out that if you leave it on for a million years, it might just accelerate a space ship of one cubic centimetre up to a few millimetres per hour.
With due apologies to the authors if this estimate turns out to be a gross underestimate.

How does this preserve momentum conservation? In the Casimir effect, the force occurs between two plates; as the plates are pushed in opposite directions, total momentum is conserved. Here, it seems as though you get momentum out of thin air (although energy is reffered to as "being spent", but with no indication how).

Quantum fluctuations of the
position or of the magneto-electric constant of particles
do not affect the average value of their momentum, as a
consequence of the conservation of momentum law.
A propulsion engine may be designed by using for instance an addressable array of small magneto-electric
particles or wires. Rotating (see Fig. 1) or aggregating
(see Fig. 2) these particles will result in velocity:

He brings up attitude control of satellites as an example because, I think, it's a situation where very small amounts of momentum do useful work (you only need to rotate the satellite by a degree or so a day, he says). He's definitely talks about propulsion in the body, not just orientation.

As reactionless drives are very much Weird Science, not mentioning propulsion in the abstract could well be entirely deliberate to make the article more

If you would read the article (a high order, I know), you would realize that, with quantum mechanics taken into consideration, there is no such thing as a classical vacuum. Hell, you could probaby get that just from reading the summary.

Yes, I know that. In fact, I already knew that. What I said is still valid for the quantum vacuum - even when the ground state has a non-zero vacuum expectation value, it still has no direction of any kind. Hence, no momentum. "Pushing the vacuum" would mean exciting it to a state where it wasn't the vacuum any more, e.g. by creating photons and directing them out of the back of the rocket. Now that's fine, but hardly revolutionary.

An EM field can carry momentum, but this allows the momentum to go in only one direction.

If I emit an EM field, it is pushing back against me as it emits (albeit VERY gently). When the EM field hits something, it imparts some or all of that momentum to the object it hits. The conservation of momentum has been maintained, because there are equal and opposite forces.

Normally, drives do one of two things to move the object they are trying to move. They either eject mass at speed in the opposite direction (rockets) which involves the loss of mass or push against something like ground or air (wheels in a car, propellers on a plane) to pull themselves forward.

In a frictionless vacuum, the only known propulsion system that works is a mass-ejection system like a rocket. You have nothing to push against that a friction drive needs, so you have to bring your own mass and throw it out to gain momentum. As you use your propellant mass, you lose it, so you have to carry some sort of mass and some sort of way of throwing it out really fast so you make the most of every gram of mass you eject.

What this new theory is suggesting is that I can get the momentum for the cost of pure energy at one end, then use that momentum on the other end of the transaction for motion. Normally, I'd either have to have something to push against that would move back in the opposite direction as a result (or would be so huge that the opposing force would be negligible), or I'd have to eject mass.

This drive would do neither - it's like pulling yourself up by your own bootstraps (quite literally) then using the energy of your pulling to allow you to move through the air. The conservation of momentum, equal and opposite reactions, etc - poof - all gone. This is truly a non-Newtonian drive in that it appears to break fundamental laws of Newtonian physics.

Unless, of course, there is something that is "absorbing" the other side of the "equal and opposite" reaction, something outside our ability to perceive at this point, in which case this is a friction drive, we just haven't figured out what we are pushing against yet.

Sorry, the "coolness" of this theory is hard to explain, which is also the reason the theory is so unlikely (but would be SO COOL if it's true!)

Currently, if I want to move an object, I need to receive and/or cause some sort of external reaction in the opposite direction to do it. Either I push against something or something pushes against me, or I eject mass in one direction at speed to move in another. Something in my surrounding environment is required for me to act against, or I need to change the env

It's hard for an old SF fan like me to admit it, but I think the implications of this paper on possibly how EM fields propagate might be even more interesting than its application as a drive. EM is an electric field collapsing to become a magnetic field, which collapses to become an electric field, rinse and repeat. How often this happens is the frequency of the EM wave system. Aren't we running up against some sort of frequency limit here, to get EM affect against quanta? Is there a maximum number for this? And at these higher limits, will there be some split between the E and the M portions of the wave? Jus' curious, but I suspect there's a few papers waiting to be writ along those lines.

Yes it does. The field is generated from the virtual particles in the vacuum, not from the ship. It is that field that they add momentum to -- the article explicitly mentions doing this -- adding equal and opposite momentum to their ship. They aren't trying to 'drag' the quantum vacuum field along with them. That would be impossible, not a method of propulsion, and violate conservation of momentum. The actual idea, however, does not.

It would be if Charlie Daniels is right. Or that that was what he was saying.

Maxwell says you can conserve momentum and still gain propulsion by emitting radio waves.

BTW, that isn't the laws of thermodynamics, more like the laws of motion. It's a momentum and energy not being the same thing and each having its own conservation law, sort of thing.

But take heart. Most jokes are funny not because they are right, but because they follow the syntactic and semantic patterns of jokes. Same deal with Republican political slogans. Total bullshit, but excellent clap-trap.

Does a demonstration of the Casimir effect produce energy? If not, based on your reasoning above, why not? It would seem to me that having the plates really close to each other, so that only certain wavelengths could exist in the space between them would result in non-uniform or changed virtual particles, so that something would be left over.

"You can't see moons around Jupiter. If there were, it would mean the Earth isn't the center of the universe." (Galileo's critics really said this.)

"You can't sail across the Atlantic to China. If you could, it would mean the Earth was round" (many, many errors on all sides of that statement!)

"Anyone who is talks about the practical uses of nuclear power is talking moonshine" (Rutherford in 1920, more-or-less.)

Scientific progress is the process of tearing down previously believed truths as well as discovering new, hopefully somewhat less contingent truths (although of course non-zero contingency always remains, which is a big deal to philosophers,mathematicians and other insane people, but not something anyone else cares very much about.)

People who have done actual calculations, rather than an arm-chair analysis on/., think that it is possible to change the momentum of vacuum modes, thereby making them non-vacuum modes (one would presume) by introducing asymmetries from rotating magneto-electric materials and in various other ways.

Introducing asymmetries has long been know to produce real particles from the vacuum. One of the most dramatic theoretical instances of this is a step-function potential with more than twice the electron mass. If you solve the Dirac equation in this situation you get weird phenomena like negative transmission and reflection coefficients that are negative or greater than unity.

The explanation is that such a large potential (so long as the step occurs over a scale of less than the Compton wavelength of the electron, which is about a pico-metre) has the ability to separate the virtual pairs that make up the "Dirac sea", thus turning them into actual particles (at the cost of the required amount of energy). If you could actualize this you could then accelerate the electron and positron to fire them off in the same direction, giving your apparatus a push in the process. At the most abstract level, what these guys are proposing is no different from that.

"You can't sail across the Atlantic to China. If you could, it would mean the Earth was round" (many, many errors on all sides of that statement!)

The main error being the claim that it was ever a serious criticism; a myth that appears to have been created by erroneous 19th century writings about Columbus. By the time anyone Europeans were looking for better trade routes to China and the Indies, both that the Earth was round and its rough diameter had been established for many centuries, and in fact navigati

My thoughts exactly. Not to mention if "energy is being spent" that means the mass of the object is decreasing (i.e. the whole mass-energy equivalence thing). If this effect is actually real, then somehow there's still energy being thrown out in the opposite direction to conserve momentum, so I'm not sure how it would be any different than any other form of propulsion. The only advantage I could see is that perhaps using this effect produces a higher specific impulse than other modes of propulsion?

OK from the article they're "changing the momentum of the electromagnetic fields in a quantum vacuum". Basically that just means they're throwing photons out the back. That is still going to decrease the rest of mass of whatever it is that powering it. So what's the specific impulse of this method?

Yes that's correct, virtual photons. A photon is the carrier of the electromagnetic force and is the quanta that makes up the field, so any electromagnetic interaction can be thought of as an exchange of virtual photons, that is, photons that appear spontaneously out of the vacuum. http://en.wikipedia.org/wiki/Virtual_particle [wikipedia.org]

Given that there is little friction in space, I wonder if it would be possible to generate and store energy when slowing down at the end of the journey (like a hybrid car) and use it to accelerate back up to speed again on the next trip.

This would dramatically reduce the overall energy consumption, but would need some serious energy storage capacity.

What they've done is create something that spins around, and in the process pushes off of something else, generating propulsion.

In other words.... They just invented the space-wheel! The question of powering the spinny parts is still up in the air, you'll need some sort of engine. The parallels to automobiles should be obvious to any experianced slashdotter.:)

Is dumping momentum into the quantum vacuum different from emitting photons carrying the same momentum? If not, this is just a photon drive, which is a well known concept, has brilliant specific impulse but is incredibly energy-inefficient except at high relatavistic velocities.

You don't have to "emit" anything, you just set up magnetic fields to push against the "vacuum" of space, which is not at all a true, classical vacuum (it contains little fields all over the place). It's like the ocean, a force that can be interacted with. A "working fluid".

And since we're talking electromagnetism, a really strong force in the grand scheme of things, maybe this will be a lot of energy efficient that simply throwing almost-massless particles out your rear.

I did read that article. It didn't answer the question. The quantum vacuum consists of (at the energy levels we're dealing with) virtual photons. If we're giving net momentum to these virtual photons I think that is the same thing as there being real photons travelling in the appropriate direction. So, you move some charges and magnetic dipoles around, and you photons start moving -- how is this different from emitting something from an antenna?

And since we're talking electromagnetism, a really strong force in the grand scheme of things, maybe this will be a lot of energy efficient that simply throwing almost-massless particles out your rear.

Since it is a momentum-transfer (hence, reaction) drive, it would seem to face the same constraints as any such drive imposed by conservation of energy, so in the ideal case, it would perform exactly the same as an ideal photon drive. Of course, engineering efficiencies might, in practice, favor one over the other, but even an ideal photon drives has an enormous input power to thrust ratio on the order of 300MW per Newton of thrust.

Something like this is probably the only chance there is for interstellar space travel. The two biggest problems in traveling between stars are first having a source of energy that will last long enough to make it there, and second having the mass for propulsion needed to make it there. Between stars, there's not a lot you can push against so you have to carry your mass with you, and for corrections on an interstellar flight that could add up to a lot of mass. Either that or hope when you shoot out of the S

If I'm reading the summary right, that's basically a reactionless drive: a device that can accelerate in space without having to throw anything out the back.

A reactionless drive would be nifty because it can gather kinetic energy very easily (that's what makes travel so cheap with one). However, there's a darker side to that coin. If you can accelerate a ship to near-c with little difficulty, there's not much stopping you from extorting the Earth by threatening to drop the ship (or for that matter, a bunch of tungsten telephone poles traveling at.99c) on them.

Any propulsion system can be used as a weapon. Thus, the good news of the reactionless drive is that one can easily move about in space. The bad news is that one will have to.

Considering most other forms of theoretical space propulsion are accomplished with either controlled explosions (the bigger the better) or exceedingly large lasers, this seems relatively safe. Besides, sending something up to.99c still takes an extreme amount of energy, even if the system were 100% efficient (which I highly doubt) getting any sizable object up to that speed is going to take a massive power supply; massive enough that it could probably have been used more directly if you wanted a weapon.

If you can accelerate a ship to near-c with little difficulty, there's not much stopping you from extorting the Earth by threatening to drop the ship (or for that matter, a bunch of tungsten telephone poles traveling at.99c) on them.

Well, you could.

Alternatively, since all that kinetic energy doesn't come out of nowhere, you'd still need to supply a really huge battery. And if you've got one of those, there's probably more convenient ways to use it to kill people than all that inconvenient fiddling about with spaceflight.

Uuum, wouldn’t it be more like a machine that constantly digs up some soil, and throws it behind itself, to accelerate?

Of course, here the “soil” constantly digs itself up. But you’re still “taking that “stuff”, and throwing it behind yourself. It just happens to zero itself out after this, if I understand it correctly.

I would bet money, that we will get some very interesting effects and new science out of even trying this.Like finding out why it does not work. Or w

"Although the proposed engine will consume energy for manipulation of the particles, the propulsion will occur without any loss of mass," says Feigel.

I'd like to see how that works. The one thing that even non-physicists know is that energy is equivalent to mass (E=mc2). This applies to all power. However the mass loss of a battery which discharges is negligible compared to the total mass hence it is usually neglected for energies below nuclear. Unless they can show otherwise my very strong suspicion is that they energy needed to manipulate the nano-particles will be identical to the energy needed to emit a photon of the same momentum. Until they can sh

I see plenty to be excited about. For one, you're not having to chuck stuff out the back. With a rocket, you are carrying your reaction mass along with you. You're not only having to accelerate your ship, you're having to accelerate the stuff you'd just gonna throw out the rear a few minutes from now. It means that ships are very heavy and inefficient.

With this, you're just concerned about your energy. Without it, you're concerned about your energy, and the extra mass you have to carry along with you,

Does it mean that I am old because I look around every day and it feels like I am living in a surreal sci-fi story?

Reactionless drives, energy weapons, smart phones, robotic killing machines, genetically engineered super species? At this rate I wonder if I would be surprised when practical AI or faster than light travel becomes an option.

"According to quantum mechanics, a vacuum will be filled with electromagnetic waves leaping in and out of existence."

I'm confused. . . does this violate the law of the Conservation of Matter & Energy? Can this effect be exploited to harness 'free' energy? After all, electromagnetic waves are energy, are they not? Sure, propulsion that doesn't require you to throw stuff out the back door sounds interesting, but free energy sounds even more interesting.

No. Think of the virtual particles as a loan that *must* be repaid. The more that is loaned, the quicker that it must be repaid. electron/positron virtual pairs exist for a loner time than say virtual proteon/antiproton pairs do. There is no way to use the creation of virtual pairs to create free energy or break the conservation laws.

He started with the fact that electrical and magnetic forces between objects are mediated by photons that flit between them. So an object placed in strong electric and magnetic fields can be considered to be immersed in a sea of these transitory, virtual photons.

Feigel then showed that the momentum of the virtual photons that pop up inside a vacuum can depend upon the direction in which they are travelling. He concludes that if the electric field points up and the magnetic field points north, for example, then east-heading photons will have a different momentum from west-heading photons.

So the vacuum acquires a net momentum in one direction — it’s as though the empty space is ‘moving’ in that direction, even though it is empty.

It is a general principle of physics that momentum is ‘conserved’ — if something moves one way, another thing must move the other way, as a gun recoils when it shoots a bullet. So when the vacuum acquires some momentum from these virtual photons, the object placed within it itself starts to move in the opposite direction.

Feigel estimates that in an electric field of 100,000 volts per metre and a magnetic field of 17 tesla — both big values, but attainable with current technology — an object as dense as water would move at around 18 centimetres per hour.

The paper is a one-author publication in a non-peer-reviewed journal and doesn't seem to be published anywhere else. The author's affiliation is an applied R&D institute not an academic institute with a strong theoretical background. I'm not saying that discredits it, but it certainly means that it should be taken with a grain of salt. I would suggest that anyone who wants to assess the merits should read through some of the references (which are good publications) and see if the present article appears plausible. Even without any technical expertise, the abstracts could probably provide a feel for the state of the art.

I couldn't be bothered to do that reading myself, but I would suggest that any momentum transfer to the vacuum would involve the production of real particles from the zero-point fluctuations. Conservation of momentum demands that there would be something carrying momentum in the opposite direction of the spacecraft and, by definition, it can't be an unexcited quantum field. There would have to be excitations of the field to carry the momentum (real particles).

Something that nobody has mentioned yet is that if we're coupling to the surrounding vacuum to accelerate ourselves, we should be able to couple to the vacuum to decelerate ourselves, _and store the energy from the deceleration_.

Given big enough energy storage devices, we can then use that energy to accelerate on the next trip, and the net energy cost per trip is substantially reduced.

Well you're not going to get to a decent fraction of light speed if you need to squirt stuff out of the back of a rocket. A propulsion system that doesn't depend on squirting stuff out of the back of the ship opens up all sorts of possibilities.

E.g. a spaceship that could accelerate at 1g would have all sorts of useful properties. Firstly 1g feels like gravity. Secondly you could zip around the solar system pretty quickly. Last but not least, due to time dilation you could circumnavigate the known universe in 50 to 100 years ship time. Of course back on Earth millions of years would pass so the trip would be one way. Still you could imagine making decades long (I guess, I'm too lazy to do the math) trips to a star like Sirius.

Actually I like the idea of sending out a plague of self replicating machines in devices like these, to bring the Word Of Dawkins to the stars and troll the inhabitants of other star systems.

Actually I like the idea of sending out a plague of self replicating machines in devices like these, to bring the Word Of Dawkins to the stars and troll the inhabitants of other star systems.

The idea of sending out self-replicating devices doesn't depend on this very much. Using standard propulsion and gravity slingshots, we can get objects to about 1/1000 speed of light, and so it will just take that much longer for our self-replicating devices to get where they are going. It's not like they need to be in a hurry. And such devices should be realizable in the not-to-distant future (say, 200 years or so). Since the Milky Way is only 100,000 light years across, it would take only take 100,000

And if other intelligent life has done this, then there would be space probes flying around through our solar system. Maybe we're just missing them.

There are literally billions of stars in the galaxy- even if a thousand civilizations spent a sizable portion of their energy lobbing (largely pointless) space probes all over the place, there're still no guarantees that one would be in the solar system during the (astonishingly brief) period that humanity have been looking for them.

If a spacecraft carries reaction mass, the total mass of the spacecraft is increased by the amount it is carrying at any one time. This mass must also be accelerated and decelerated. So the more you carry, the more you spend because you're carrying it. There are various side effects too, for instance, since the vehicle's mass changes over time, course change calculations have to keep track of that. Also, for every bit of mass you have to carry that is fuel, that's less cargo you can move from point A to point B.

If you have an energy source that is relatively mass constant - a nuclear reactor, or a set of solar panels - and you can piddle along without any tanks full of "stuff", you're going to be able to carry more payload; you're going to be able to go a lot longer without "refueling"; you're going to have more freedom and more range. Headed for asteroid X? Something interesting over there on Asteroid Y? No bothersome fuel constraints, you just go and take a look. That's the kind of benefit that has very positive ramifications.

The reason reaction mass is used in space is because in a vacuum, one has to push against something in order to move. That's the role of the reaction mass. You spend energy in X direction and get sent off in the -X direction with the same amount of energy.

Think of how a nuclear sub works underwater. Because it has something to push against (water), its ability to move is constrained only by the degree of push it can generate - it doesn't have to carry anything to push against, it's surrounded by water that will serve the purpose. The reactor provides a lot of energy to push with, using a propeller, which is designed so as to create a forward vectored force when spinning in the water. That's what the article suggests for space craft; that there is something there to push against, and therefore, one doesn't need to carry reaction mass. Spaceships using this method would be very much analogous to that nuclear submarine.

A nuclear reactor simply converts mass to energy, very inefficiently. So just by virtue of running it, you are losing fuel mass. There's no free lunch.

In the absolute best case for an energy source, you could convert mass directly to energy, and use that to power your quantum drive. But if you can convert mass directly to energy, you can just dump that energy out the back in the form of photons and get the exact same level of thrust...maybe more if your quantum drive has any inefficiencies. So I don't reall

Your fuel source does not change its mass. The gas in your tank combines with the local air and releases pollutants into the air. Furthermore, it achieves actual movement by turning a wheel which interacts with the ground.

A spacecraft has no ground to interact with. Rockets produce movement by throwing away their mass. This engine (if it works) would not have to throw away its mass.

There are other ways to get around without throwing mass. Light sails produce it by interacting with photons that the sun (or

Getting energy into space is easy.
You can grab it from nearby stars, or
you can carry a nuclear reactor with you.
Because a nuclear reactor converts mass
to energy via E=Mc^2, it produces a lot
of energy from a small mass.

The real problem is reaction mass.
You have to have something to push against
in order to move. Getting a lot of reaction mass
into space is difficult. If you can push against
the vacuum of space, that problem is solved.

As the author of the introduction, Zee notes: "According to Feynman, to learn QED you have two choices: you can go through seven years of physics education or read this book"

This is the best book there is that I know of that will give you the grounding to get Quantum Electrodynamics. You will discover that particles do in fact, exist in a vacuum. The quantum world does not work anything like the macro world that we are used to. You have

There's no reason quantum propulsion couldn't be used on earth, except maybe it wouldn't be very efficient. It could be used to make helicopter-like machines, which levitate without distorting the air around it. Or ships that don't leave a trail. Come to think of it, this might one day be a big thing in military stealth vehicles.

The computer you're typing on is a rather good example of quantum mechanics on an industrial scale. It's been estimated that quantum mechanics is in some way responsible for a large fraction (can't remember exactly - two thirds?) of our economy.